Performance tweaks for Mojo Dart Controller

mojo/dart/embedder/dart_controller.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/path_service.h"
 #include "base/rand_util.h"
@@ skipping 594 matching lines @@
   }
 
   // Start a handle watcher.
   handle_watcher_producer_handle_ = HandleWatcher::Start();
 
   std::vector<const char*> flags;
   // Disable access dart:mirrors library.
   flags.push_back("--enable_mirrors=false");
   // Force await and async to be keywords even outside of an async function.
   flags.push_back("--await_is_keyword");
+  // Enable background compilation
+  flags.push_back("--background_compilation=true");
+  // Disable code write protection
+  // TODO(johnmccutchan): This might be a security issue once Mojo gets a
+  // security sandbox. Revisit when that happens.
+  flags.push_back("--write_protect_code=false");
   // Add remaining flags.
   for (int i = 0; i < vm_flags_count; ++i) {
     flags.push_back(vm_flags[i]);
   }
 
   tonic::DartVM::Config config;
   config.vm_isolate_snapshot = vm_isolate_snapshot_buffer;
   config.create = IsolateCreateCallback;
   config.shutdown = IsolateShutdownCallback;
   config.entropy_source = entropy;
@@ skipping 89 matching lines @@
   }
   BlockForServiceIsolateLocked();
   HandleWatcher::StopAll();
   CHECK(tonic::DartVM::Cleanup());
   service_isolate_running_ = false;
   initialized_ = false;
 }
 
 }  // namespace apps
 }  // namespace mojo